Summary of Significant Accounting Policies - Foreign Currency (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Foreign currency translation losses included in Accumulated other comprehensive loss	$ 12,849	$ 19,464	$ (4,970)
Foreign currency transaction gains (losses)	$ (1,200)	$ 2,500	$ 700